Project Summary/Abstract Individuals suffering from body dysmorphic disorder (BDD) experience peculiar misperceptions of their appearance, most often of the face or head. With convictions of disfigurement and ugliness, they typically have poor insight or even delusional beliefs, as well as obsessive thoughts and compulsive behaviors, anxiety, and depression. These combine to result in significant difficulties in functioning, as well as depression, suicide attempts (25%), and psychiatric hospitalization (50%). Despite this severity, relatively few studies of the neurobiology, or even treatment studies, have been conducted in BDD. This underscores a critical need for research seeking to identify targets for intervention based on pathophysiological mechanisms. To-date, background research conducted by our group has provided early insights into neurobiological mechanisms that may contribute to these perceptual distortions, including prominent abnormalities in visual processing systems. These, along with evidence from neuropsychological and psychophysical tests of visuospatial and visual processing, have contributed to the development of a model of diminished global/holistic processing and enhanced detail processing, attributed to both ?top-down? and ?bottom-up? disturbances in perception. However, there remain gaps in the understanding of the neurobiology that may hinder the rational development of novel and effective treatment strategies. Studies thus far have primarily been cross-sectional and few have explored the effects of visual manipulation in order to probe for dynamic abnormalities. Accordingly, this study aims to illuminate the pathophysiology underlying perceptual distortions in BDD using two novel visual modulation techniques: a) attention modulation (?top-down?) and brief image presentation (?bottom-up?) to probe the visual system. We will enroll 34 individuals with BDD and 34 healthy controls, who will undergo two experiments involving viewing photographs of their face while being scanned using functional magnetic resonance imaging (fMRI). In the attention modulation experiment, they will be given instructions and training to hold their gaze constant in order to increase fixation duration and decrease scanning of appearance details, which we hypothesize will increase dorsal visual stream (global/holistic processing) and decrease ventral visual stream (local/detail processing) activation in the brain. In the second experiment we will test whether brief face viewing time increases activity in dorsal visual areas. Results from this study will advance our understanding of the neurobiological basis of perceptual distortions in BDD and identify neurobiological treatment targets for future testing of novel, translational perceptual retraining treatments.